Materials that can be stimulated to emit
light, commonly referred to as luminescent materials or luminophors, can be employed in a wide variety of applications. In a simple application a luminophor can be employed to absorb ultraviolet radiation and emit visible light. In other applications one of a variety of different stimulating sources of radiation, such as electrons, .alpha. or .beta. particles, .gamma. rays or X rays, can be employed. In still another type of application, referred to as electroluminescence, the recombination of hole-electron pairs can provide the stimulating energy source for luminescence.
For many luminophor applications there is a need for thin (&lt;1 .mu.m) film luminophors. Often the evironment for deposition is incompatible with coating from solution. Thus, for many applications the luminophors must be capable of being deposited as thin films from a vapor phase. Vapor phase deposition offers the advantages of well controlled film thicknesses, both in terms of uniformity and the rate at which they are formed. Since only the luminophor is required for vapor phase deposition, very high purity films can be formed. Specific examples of luminophors used to construct thin films in an environment requiring vapor deposition are provided by VanSlyke et al U.S. Pat. No. 4,539,507, Tang et al U.S. Pat. No. 4,769,292, VanSlyke et al U.S. Pat. No. 4,720,432, Tang et al U.S. Pat. No. 4,885,211 and Perry et al U.S. Pat. No. 4,950,950.
Through a series of investigations conducted over a period of years preferred green-emitting luminoph,ors capable of vapor deposition and exhibiting high levels of luminescence efficiencies and stabilities have been found to be aluminum trisoxines, a.k.a. tris(quinolinolato)aluminum(III) chelates. Unfortunately, these chelates are green-emitting luminophors and do not satisfy the need in the art for blue-emitting luminophors having comparable qualities.